As is well known, a fuel cell is an electricity generating system that directly converts chemical reaction energy of oxygen and hydrogen contained in hydrocarbon materials such as methanol, ethanol, or natural gas into electric energy.
A polymer electrolyte membrane fuel cell (hereinafter, referred to as PEMFC) has been developed recently which has excellent output characteristics, low operating temperatures, and fast starting and response characteristics. PEMFCs have a wide range of application, including mobile power sources for vehicles, distributed power sources for homes or buildings, and small-size power sources for electronic apparatuses.
A fuel cell system employing the PEMFC scheme includes a stack, a reformer, a fuel tank, and a fuel pump. The stack includes an electricity generator and has a plurality of unit cells and the fuel pump supplies a fuel stored in the fuel tank to the reformer. Then, the reformer reforms the fuel to generate hydrogen and supplies hydrogen to the stack, which generates electric energy through an electrochemical reaction between the hydrogen and oxygen.
The reformer is a device for generating hydrogen from the fuel containing hydrogen through a catalytic chemical reaction using thermal energy. Generally, the reformer includes a heat source for generating the thermal energy, a reforming reactor for generating the hydrogen gas from the fuel using the thermal energy, and a carbon-monoxide remover for reducing the concentration of carbon monoxide contained in the hydrogen gas.
In a conventional reformer of a fuel cell system, the heat source, the reforming reactor, and the carbon-monoxide remover are each formed in a vessel shape and are connected and separated through pipes. Accordingly, it is difficult to compactly embody the fuel cell system and to rapidly deliver the thermal energy generated from the heat source to the reforming reactor, thereby deteriorating reaction efficiency and thermal efficiency of the entire fuel cell system.